testing/radix-tree/maple: Hack around kfree_rcu not existing

liburcu doesn't have kfree_rcu (or anything similar). Despite that, we
can hack around it in a trivial fashion, by adding a wrapper.

The wrapper only works for maple_nodes because we cannot get the
kmem_cache pointer any other way in the test code.

Link: https://lore.kernel.org/all/[e-mail]/
Suggested-by: Pedro Falcato <[e-mail]>
Signed-off-by: Liam R. Howlett <[e-mail]>
Reviewed-by: Suren Baghdasaryan <[e-mail]>
Signed-off-by: Vlastimil Babka <[e-mail]>

tools/testing/shared/maple-shared.h

···
 #include <time.h>
 #include "linux/init.h"
 
+void maple_rcu_cb(struct rcu_head *head);
+#define rcu_cb		maple_rcu_cb
+
+#define kfree_rcu(_struct, _memb)		\
+do {                                            \
+    typeof(_struct) _p_struct = (_struct);      \
+                                                \
+    call_rcu(&((_p_struct)->_memb), rcu_cb);    \
+} while(0);
+
+
 #endif /* __MAPLE_SHARED_H__ */

tools/testing/shared/maple-shim.c

···
 #include <linux/slab.h>
 
 #include "../../../lib/maple_tree.c"
+
+void maple_rcu_cb(struct rcu_head *head) {
+	struct maple_node *node = container_of(head, struct maple_node, rcu);
+
+	kmem_cache_free(maple_node_cache, node);
+}